Star Corsairs

Star Corsairs is a browser-based MMORPG in which players must repel the constant alien threat against humanity. Players can explore outer space while keeping an eye on aliens, asteroids of interest and other players if they wish to engage in PvP.Players looking for a more peaceful experience will love the manufacturing system allowing them to create and customize all components required by spaceships.

Star Corsairs features include:

• Real-time epic space battles
• Pilot fast fighters or powerful capital spaceships
• Create and upgrade components for your spaceships
• Travel anywhere in the galaxy without any restriction
• Fight aliens, mine asteroids or engage in PvP battles
• Public missions to easily find players to play with
• Form an alliance and conquer space systems

It's a free-to-play browser game, so it should be pretty easy to jump in and check out.
Here's the trailer: